Use of supported rhodium catalysts in the preparation of tertiary butyl alcohol from tertiary butyl hydroperoxide

Abstract: A method for preparing tertiary butyl alcohol wherein a feedstock comprising a solvent solution of tertiary butyl hydroperoxide in tertiary butyl alcohol or a mixture of tertiary butyl alcohol with isobutane is charged to a hydroperoxide decomposition reaction zone containing a catalytically effective amount of a hydroperoxide decomposition catalyst consisting essentially of alumina or carbon having rhodium deposited thereon and is brought into contact with the catalyst in liquid phase under hydroperoxide decomposition reaction conditions to convert the tertiary butyl hydroperoxide to decomposition products, principally tertiary butyl alcohol.

Description: This invention relates to the catalytic decomposition of tertiary butyl hydroperoxide (TBHP). More particularly, this invention relates to a method for the preparation of tertiary butyl alcohol (TBA) by the catalytic decomposition of tertiary butyl hydroperoxide. Still more particularly, this invention relates to a method wherein an alumina or carbon supported rhodium catalyst is used to catalyze the substantially selective decomposition of tertiary butyl hydroperoxide to tertiary butyl alcohol. It is known to react isobutane with oxygen, either thermally or catalytically, to form a peroxidation reaction product wherein the principal peroxide that is formed is tertiary butyl hydroperoxide. It is also known to thermally or catalytically decompose the tertiary butyl hydroperoxide to form tertiary butyl alcohol. US-A-4,704,482 (Sanderson et al.) discloses a method for catalytic purification of motor-grade tertiary butyl alcohol, contaminated with low (e.g. 1.5 x 10 -3 parts) levels of TBHP. A rhodium-on-alumina catalyst is described, inter alia. Conversion of high levels of TBHP is not described. Sanderson et al. also disclose the use of a variety of catalysts for the decomposition of tertiary butyl hydroperoxide in a series of U. S. patents, including a catalyst composed of iron, copper, chromia and cobalt (U. S. Patent No. 4,705,903), a catalyst composed of a base treated hydrogenation catalyst from groups VIA or VIII of the Periodic Table (U. S. Patent No. 4,742,179), a catalyst consisting essentially of nickel, copper, chromium and barium (U. S. Patent No. 4,873,380), a catalyst composed of a metal phthalocyanine promoted with a rhenium compound (U. S. Patent No. 4,910,349), a catalyst composed of a base promoted metal phthalocyanine compound (U. S. Patent No. 4,912,269), a catalyst composed of a soluble ruthenium compound promoted with a bidentate ligand (U. S. Patent No. 4,912,033), a catalyst composed of a metal porphine such as iron (III) or manganese (III) promoted with an alkyl thiol or an amine, a catalyst composed of an imidazole promoted metal phthalocyanine compound (U. S. Patent No. 4,912,266), (U. S. Patent No. 4,922,034), a catalyst composed of a metal phthalocyanine promoted with a thiol and a free radical inhibitor (U. S. Patent No. 4,922,035), a catalyst composed of a borate promoted metal phthalocyanine (U. S. Patent No. 4,922,036), or a catalyst composed of a soluble ruthenium compound and an iron compound such as an acetate, a borate, a bromide, a chloride, a 1,3-propanedionate, a 2-ethyl-hexanoate, an iodide, a nitrate, a 2,4-pentanedionate, a perchlorate or a sulfate (U. S. Patent No. 5,025,113). As stated, when isobutane is reacted with molecular oxygen, the principal products of the reaction are tertiary butyl alcohol and tertiary butyl hydroperoxide. However, minor amounts of other contaminants are also formed. A minor amount of water will be formed, which will normally amount to 0.5 to 1 wt.% of the reactor effluent. The amount of byproduct water that is produced is a function of the severity of the reaction conditions employed and will tend to increase as the severity of the reaction conditions is increased. As indicated, tertiary butyl hydroperoxide is useful as a raw material for the manufacture of tertiary butyl alcohol. The tertiary butyl alcohol can be formed by catalytic decomposition of the tertiary butyl hydroperoxide. US-A-3,472,876 discloses a process wherein an oxygen-containing gas was charged to a reactor containing isobutane and an oxidation catalyst to provide a reaction mixture comprising tertiary butyl alcohol, tertiary butyl hydroperoxide, acetone, and tertiary butyl ether. The reported results in the patent indicate that there was a comparatively low rate of conversion and a comparatively poor selectivity of the reaction to tertiary butyl alcohol. There is a need for a catalytic decomposition of tertiary butyl hydroperoxide to tertiary alcohol at a higher conversion rate and an improved selectivity over the prior art. In accordance with the present invention, a solvent solution of a tertiary butyl hydroperoxide charge stock is brought into contact with a catalytically effective amount of a hydroperoxide decomposition catalyst in a hydroperoxide decomposition reaction zone in liquid phase with agitation to convert the tertiary butyl hydroperoxide to decomposition products, principally tertiary butyl alcohol, the hydroperoxide decomposition catalyst being a supported hydroperoxide decomposition catalyst consisting essentially of alumina or carbon having deposited thereon from 0.01 to 1 wt.%, preferably 0.1 to 1 wt.%, of rhodium and tertiary butyl alcohol is recovered from the products of the hydroperoxide decomposition reaction. The starting materials for the process of the present invention are a tertiary butyl hydroperoxide feedstock and a supported rhodium catalyst. The Tertiary Butyl Hydroperoxide Feedstock The tertiary butyl hydroperoxide charge stock may comprise an isobutane oxidation product wherein the tertiary butyl hydroperoxide is dissolved in a mixture of isobutane and tertiary butyl alcohol or may comprise an isobutane oxidation product enriched by the addition of tertiary butyl alcohol, such that the solution of tertiary butyl alcohol in the mixture of isobutane with tertiary butyl alcohol contains from 5 to 30 wt.% of tertiary butyl hydroperoxide. Alternatively, the isobutane reaction product may be charged to a distillation zone where unreacted isobutane is removed as a distillate fraction for recycle to thereby provide a solution of tertiary butyl hydroperoxide in tertiary butyl alcohol containing 5 to 30 wt.% of tertiary butyl hydroperoxide. The Catalyst System The hydroperoxide decomposition catalyst to be used in accordance with the present invention is a supported hydroperoxide decomposition catalyst consisting essentially of alumina or carbon having deposited thereon from 0.01 to 1 wt.%, preferably 0.1 to 1 wt.%, of rhodium. Catalytic Decomposition of Tertiary Butyl Hydroperoxide The process of the present invention may be conducted batchwise in kettles or by continuously passing the reactants through a tubular reactor. The catalytic decomposition of the tertiary butyl hydroperoxide is preferably conducted at a temperature within the range of 20° to 250°C, preferably 60° to 120°C, and more preferably at a temperature within the range of 80° to 100°C. The reaction is preferably conducted at a pressure sufficient to keep the reactants and the reaction products in liquid phase. A pressure of 0.1 to 7.0 MPa (0.1 to 1,000 psig) may be used if desired. Flow rates of the charge solution to the reaction zone should be adjusted in order to provide an appropriate contact time within the reactor. In a batch process, the holding time may suitably be from 0.5 to 10 hours, and more preferably 1 to 3 hours. In accordance with the most preferred embodiment of the present invention, isobutane is reacted with oxygen in an oxidation zone under oxidation reaction conditions including a temperature of 135 to 155°C., a pressure of 2.1 to 5.6 MPa (300 to 800 psig), and a holding time of 2 to 6 hours to provide an initial oxidation reaction product comprising unreacted isobutane, tertiary butyl hydroperoxide, tertiary butyl alcohol, and oxygen-containing by-products. The initial oxidation reaction product is then used as the tertiary butyl hydroperoxide charge stock of the present invention. If the concentration of tertiary butyl hydroperoxide in the tertiary butyl hydroperoxide charge stock is more than 30 wt.% of the initial oxidation reaction product, the initial oxidation reaction product can be diluted with an amount of tertiary butyl alcohol sufficient to lower the concentration of the tertiary butyl hydroperoxide to a desired percentage, to provide, for example, a tertiary butyl hydroperoxide charge stock containing from about 15 to 25 wt.% of tertiary butyl hydroperoxide. Alternatively, the initial oxidation reaction product may be fractionated in any appropriate manner (e.g., by distillation in a distillation zone) to remove the isobutane therefrom for recycle and to provide a solution of tertiary butyl hydroperoxide and tertiary butyl alcohol which will normally contain from 5 to 30 wt.% of tertiary butyl hydroperoxide. The solution of tertiary butyl hydroperoxide in tertiary butyl alcohol is then charged to a catalytic hydroperoxide decomposition zone where it is brought into contact with a carbon or alumina supported rhodium catalyst to substantially selectively convert the tertiary butyl hydroperoxide to tertiary butyl alcohol with high yields and selectivities. When the process of the present invention is practiced in a continuous manner by continuously charging the tertiary butyl hydroperoxide charge stock to a reactor containing a fixed bed of pelleted hydroperoxide decomposition catalyst, the space velocity is suitably in the range of 0.5 to 3 volumes of tertiary butyl hydroperoxide charge stock per volume of catalyst per hour. Preferably, the space velocity is within the range of 1 to 2 volumes of tertiary butyl hydroperoxide charge stock per volume of catalyst per hour. The reaction product from the tertiary butyl hydroperoxide decomposition step may then be fractionated in any suitable manner, such as by distillation to recover the tertiary butyl alcohol. EXAMPLES The invention will be further illustrated by the following non-limiting examples. Procedure The reactor that was used for the experiments was a stainless steel tube (12.3 x 360mm) which was electrically heated. Liquid feed was pumped into the bottom of the reactor using a Ruska® dual drive pump. Pressure was regulated using a Skinner Uni-Flow® valve and a Foxboro® controller. Samples were collected at the top of the reactor, cooled to ambient temperature, filtered and analyzed by Gas Chromatography. The analysis of the feed and of the products obtained is reported in the following tables. CATALYTIC CONVERSION OF TERT-BUTYLHYDROPEROXIDE TO TERT-BUTYLALCOHOL RUN A 1 2 3 4 Catalyst 0.5% Rh on Al 2 O 3 0.5% Rh on Al 2 O 3 0.5% Rh on Al 2 O 3 0.5% Rh on Al 2 O 3 Catalyst (cc) 100 100 100 100 Pressure (MPa) 3.5 3.5 3.5 3.5 Feed Rate (cc/Hr.) 50 50 50 50 Temperature (°C) 80 100 120 140 Time on Stream (Hr) 4 4 4 4 Space Vel. (cc/cc) 0.5 0.5 0.5 0.5 TBHP Conversion (mol.%) 100.0 98.4 99.8 99.9 Selectivity IC4= (mol.%) -0.0 0.0 0.0 0.0 Sel. Acetone (mol.%) 12.4 27.2 37.8 45.3 Sel. Methanol (mol.%) 2.0 5.7 6.9 8.4 Sel. TBA (mol.%) 81.5 69.7 61.2 54.3 Sel. DTBP (mol.%) 6.1 3.0 0.9 0.4 Remarks H 2 O Free Basis H 2 O Free Basis H 2 O Free Basis H 2 O Free Basis H 2 O Free Basis Composition, wt% IC4= 0.001 0.000 0.002 0.003 0.003 MEOH/MF 0.016 0.153 0.401 0.486 0.588 Acetone 0.008 1.540 3.314 4.665 5.590 TBA 79.968 95.506 94.616 92.984 92.409 DTBP 0.055 1.005 0.520 0.201 0.117 TBHP 19.146 0.000 0.305 0.042 0.016 CATALYTIC CONVERSION OF TERT-BUTYLHYDROPEROXIDE TO TERT-BUTYLALCOHOL RUN A 5 6 7 8 Catalyst 0.5% Rh on Al 2 O 3 0.5% Rh on Al 2 O 3 0.5% Rh on Al 2 O 3 0.5% Rh on Al 2 O 3 Catalyst (cc) 100 100 100 100 Pressure (MPa) 3.5 3.5 3.5 3.5 Feed Rate (cc/Hr.) 100 100 100 100 Temperature (°C) 80 100 120 140 Time on Stream (Hr) 4 4 4 4 Space Vel. (cc/cc) 1.0 1.0 1.0 1.0 TBHP Conversion (mol.%) 80.1 96.4 99.8 100.0 Selectivity IC4= (mol.%) 0.0 -0.0 0.1 0.0 Sel. Acetone (mol.%) 11.9 23.2 37.6 33.6 Sel. Methanol (mol.%) 1.8 6.0 7.9 14.7 Sel. TBA (mol.%) 81.5 74.3 61.4 66.0 Sel. DTBP (mol.%) 6.6 2.5 1.0 0.3 Remarks H 2 O Free Basis H 2 O Free Basis H 2 O Free Basis H 2 O Free Basis H 2 O Free Basis Composition, wt% IC4= 0.001 0.001 0.000 0.009 0.001 MEOH/MF 0.016 0.116 0.410 0.552 4.156 Acetone 0.008 1.187 2.770 4.632 4.156 TBA 79.968 91.659 93.584 93.180 93.599 DTBP 0.055 0.874 0.430 0.215 0.100 TBHP 19.146 3.808 0.685 0.039 0.000 CATALYTIC CONVERSION OF TERT-BUTYLHYDROPEROXIDE TO TERT-BUTYLALCOHOL RUN A 9 10 11 12 Catalyst 0.5% Rh on Al 2 O 3 0.5% Rh on Al 2 O 3 0.5% Rh on Al 2 O 3 0.5% Rh on Al 2 O 3 Catalyst (cc) 100 100 100 100 Pressure (MPa) 3.5 3.5 3.5 3.5 Feed Rate (cc/Hr.) 200 200 200 200 Temperature (°C) 80 100 120 140 Time on Stream (Hr) 4 4 4 4 Space Vel. (cc/cc) 2.0 2.0 2.0 2.0 TBHP Conversion (mol.%) 56.7 90.5 99.5 99.9 Selectivity IC4= (mol.%) 0.0 -0.0 0.0 0.1 Sel. Acetone (mol.%) 10.6 19.1 39.8 51.3 Sel. Methanol (mol.%) 1.7 5.1 8.8 10.3 Sel. TBA (mol.%) 82.6 78.0 59.4 48.4 Sel. DTBP (mol.%) 6.8 3.0 0.8 0.2 Remarks H 2 O Free Basis H 2 O Free Basis H 2 O Free Basis H 2 O Free Basis H 2 O Free Basis Composition, wt% IC4= 0.001 0.001 0.000 0.005 0.007 MEOH/MF 0.016 0.082 0.328 0.609 0.717 Acetone 0.008 0.749 2.137 4.890 6.338 TBA 79.968 88.220 92.537 92.489 90.901 DTBP 0.055 0.652 0.470 0.181 0.090 TBHP 19.146 8.282 1.814 0.092 0.013 CATALYTIC CONVERSION OF TERT-BUTYLHYDROPEROXIDE TO TERT-BUTYLALCOHOL RUN A 13 14 15 16 Catalyst 0.5% Rh on C 0.5% Rh on C 0.5% Rh on C 0.5% Rh on C Catalyst (cc) 50 50 50 50 Pressure (MPa) 3.5 3.5 3.5 3.5 Feed Rate (cc/Hr.) 25 25 25 25 Temperature (°C) 80 100 120 140 Time on Stream (Hr) 4 4 4 4 Space Vel. (cc/cc) 0.5 0.5 0.5 0.5 TBHP Conversion (mol.%) 99.4 99.6 99.9 99.9 Selectivity IC4= (mol.%) 0.0 0.1 0.7 39.7 Sel. Acetone (mol.%) 16.9 18.9 23.0 30.8 Sel. Methanol (mol.%) 1.3 1.8 3.4 4.4 Sel. TBA (mol.%) 72.3 72.7 70.3 69.0 Sel. DTBP (mol.%) 10.7 8.3 6.7 0.2 Remarks H 2 O Free Basis H 2 O Free Basis H 2 O Free Basis H 2 O Free Basis H 2 O Free Basis Composition, wt% IC4= 0.001 0.003 0.016 0.082 4.727 MEOH/MF 0.016 0.103 0.136 0.250 0.315 Acetone 0.008 2.084 2.335 2.839 3.804 TBA 79.968 94.320 94.507 94.269 89.139 DTBP 0.055 1.711 1.342 1.095 0.081 TBHP 19.146 0.114 0.079 0.024 0.012 CATALYTIC CONVERSION OF TERT-BUTYLHYDROPEROXIDE TO TERT-BUTYLALCOHOL RUN A 17 18 19 20 Catalyst 0.5% Rh on C 0.5% Rh on C 0.5% Rh on C 0.5% Rh on C Catalyst (cc) 50 50 50 50 Pressure (MPa) 3.5 3.5 3.5 3.5 Feed Rate (cc/Hr.) 50 50 50 50 Temperature (°C) 80 100 120 140 Time on Stream (Hr) 4 4 4 4 Space Vel. (cc/cc) 1.0 1.0 1.0 1.0 TBHP Conversion (mol.%) 99.4 99.4 99.8 100.0 Selectivity IC4= (mol.%) 0.5 0.2 1.2 8.0 Sel. Acetone (mol.%) 20.2 22.9 26.8 32.8 Sel. Methanol (mol.%) 1.4 2.7 4.2 6.0 Sel. TBA (mol.%) 73.2 72.3 70.1 66.3 Sel. DTBP (mol.%) 6.6 4.8 3.2 0.9 Remarks H 2 O Free Basis H 2 O Free Basis H 2 O Free Basis H 2 O Free Basis H 2 O Free Basis Composition, wt% IC4= 0.001 0.063 0.023 0.146 0.957 MEOH/MF 0.016 0.110 0.197 0.301 0.425 Acetone 0.008 2.490 2.813 3.305 4.054 TBA 79.968 94.343 94.263 94.152 92.735 DTBP 0.055 1.075 0.793 0.544 0.193 TBHP 19.146 0.110 0.113 0.035 0.006 CATALYTIC CONVERSION OF TERT-BUTYLHYDROPEROXIDE TO TERT-BUTYLALCOHOL RUN A 21 22 23 24 Catalyst 0.5% Rh on C 0.5% Rh on C 0.5% Rh on C 0.5% Rh on C Catalyst (cc) 50 50 50 50 Pressure (MPa) 3.5 3.5 3.5 3.5 Feed Rate (cc/Hr.) 100 100 100 100 Temperature (°C) 80 100 120 140 Time on Stream (Hr) 4 4 4 4 Space Vel. (cc/cc) 2.0 2.0 2.0 2.0 TBHP Conversion (mol.%) 98.9 99.2 99.8 100.0 Selectivity IC4= (mol.%) 0.1 0.1 0.0 0.3 Sel. Acetone (mol.%) 23.5 25.3 23.7 30.6 Sel. Methanol (mol.%) 2.5 3.8 4.5 6.9 Sel. TBA (mol.%) 70.6 70.5 73.4 68.4 Sel. DTBP (mol.%) 5.9 4.2 3.0 1.1 Remarks H 2 O Free Basis H 2 O Free Basis H 2 O Free Basis H 2 O Free Basis H 2 O Free Basis Composition, wt% IC4= 0.001 0.018 0.009 0.003 0.039 MEOH/MF 0.016 0.186 0.273 0.319 0.483 Acetone 0.008 2.881 3.103 2.923 3.778 TBA 79.968 93.583 93.716 94.503 93.715 DTBP 0.055 0.959 0.709 0.513 0.221 TBHP 19.146 0.205 0.158 0.038 0.008 A 19.1% solution of TBHP in TBA was converted over Rh/C or Rh/Al 2 O 3 catalysts to TBA in good yields. For example, a 0.5% rhodium on alumina catalyst (80°C, 0.5 space velocity) gave 100% TBHP conversion with the following selectivities: TBA 81.5%, DTBP 6.1%, acetone 12.4%, methanol 2.0%. A Rh on carbon catalyst gave essentially the same results, i.e., almost complete conversion of the TBHP at 80°C. Typical catalysts under these conditions give 80% or less conversion. Thus, Rh/Al 2 O 3 and Rh/C catalysts are among the most active catalysts for the conversion of TBHP to TBA.

Claims: A method for the decomposition of tertiary butyl hydroperoxide to tertiary butyl alcohol, wherein a solution of a tertiary butyl hydroperoxide charge stock that contains from 5 to 30 wt.% of tertiary butyl hydroperoxide is brought into contact with a catalytically effective amount of a hydroperoxide decomposition catalyst in a hydroperoxide decomposition reaction zone in liquid phase under hydroperoxide conversion conditions including a temperature within the range of 20° to 250°C. and a pressure of 0.1 to 7 MPa (0 to 1,000 psig) to convert said tertiary butyl hydroperoxide to decomposition products, principally tertiary butyl alcohol, characterized in that said hydroperoxide decomposition catalyst comprises a carbon or alumina support rhodium. A method as claimed in Claim 1, wherein the catalyst comprises 0.01 to 1 wt.% rhodium supported on alumina or carbon. A method as claimed in Claim 1 or Claim 2, wherein the support is carbon. A method as in any one of Claims 1 to 3, wherein the temperature is in the range of 60° to 120°C.

Inventors: DURANLEAU ROGER GEORGE, KNIFTON JOHN FREDERICK, SANDERSON JOHN RONALD, DURANLEAU, ROGER GEORGE, KNIFTON, JOHN FREDERICK, SANDERSON, JOHN RONALD
Applicants: HUNTSMAN SPEC CHEM CORP, HUNTSMAN SPECIALTY CHEMICALS CORPORATION
Application year: 1994
Main classification: C07C29
IPC codes: C07B61, C07C29, C07C27, B01J23, C07C31